U.S. Pat. No. 5,155,250, issued Oct. 13, 1992 and U.S. Pat. No. 5,532,400, issued Jul. 2, 1996 disclose a class of compounds which are described by the following formula: ##STR1## wherein R.sub.1, R.sub.2, R.sub.3 and R.sub.4 are each independently a C.sub.1 -C.sub.6 alkyl group; Z is a thio, oxy or methylene group; A is a C.sub.1 -C.sub.4 alkylene group; R.sub.5 is a C.sub.1 -C.sub.6 alkyl or --(CH.sub.2).sub.n --(Ar) wherein n is an integer 0, 1, 2 or 3; and Ar is phenyl or naphthyl unsubstituted or substituted with one to three substituents selected from the group consisting of hydroxy, methoxy, ethoxy, chloro, fluoro or C.sub.1 -C.sub.6 alkyl. These patents state that the compounds are antioxidants which inhibit low density lipoprotein (LDL) lipid peroxidation and are useful as antiatherosclerotic agents. Preferred compounds of these patents include those in which R.sub.1 and R.sub.2 are tertiarybutyl; R.sub.3 and R.sub.4 are methyl or ethyl; Z is thio; A is methylene; and wherein R.sub.5 is methyl, ethyl or substituted or unsubstituted phenethyl. A particularly preferred disclosed compound of the above formula is 2,6-di-t-butyl-4-[(dimethylphenylsilyl)methyl]thiophenol.